After upgrade to Ubuntu 18.04 - Tap to click is not reliable anymore
Solution 1:
What ended up working for me was to remove the synaptics driver:
sudo apt remove xserver-xorg-input-synaptics
followed by a reboot. After that the touchpad worked again. I have a Dell XPS 15 9650.
Solution 2:
Installing Touchpad Indicator worked for me!
Solution 3:
Adjusting Mouse Settings
Sounds like you just need to do some custom configuring to your touchpad to increase the sensitivity FingerLow (minimum amount of pressure required to register a tap). This can be accomplished with synclient:
First check your settings:
$ synclient -l
Then you can adjust your FingerLow/FingerHigh (or other) settings:
$ synclient FingerLow=2
Once you figure out your correct settings you will need to put them in a startup script as the synclient options will be reset on reboot. You can see more options, get more info and learn how to make a configuration script with this Great Tutorial on Touchpad Options.
You can also use xinput to get info and tweak some settings per this Great Tutorial on Configuring HID Devices. Here is a quick summary:
First, find your device name and ID:
$ xinput --list
Look at the output to determine your device name or id number and list its available properties:
$ xinput --list-props ID
This will show you the available options you can set. Then you can set them like this:
$ xinput --set-prop ID 'prop name' VAL